Stick a tube in your mouth and sing like a robot!

A talk box is an effects unit that allows a musician to modify the sound of a musical instrument. The musician controls the modification by lip syncing, or by changing the shape of their mouth. The effect can be used to shape the frequency content of the sound and to apply speech sounds (in the same way as singing) onto a musical instrument, typically a guitar (its non-guitar use is often confused with the vocoder) and keyboards.